This invention relates to optical instruments, such as stereomicroscopes, having dual eyepiece assemblies, and more particularly stereomicroscopes having eyepiece assemblies which are rotatable to accommodate for variations in the distances between different operator's eyes.
Presently, there are several different stereomicroscopes available. In one type of microscope, for instance, the eyepieces are tilted with respect to the optical axes of the zoom lenses. This is done primarily for the comfort of the operator. In most such stereomicroscopes, the eyepiece assemblies are secured to plates which are spring loaded to the chassis of the microscope. The springs are adjustable, within certain parameters to prevent tipping of the eyepieces and to accommodate for the amount of force that is desired to rotate the eyepiece assemblies. Normally, the force required is less than one 1 b. Because the eyepieces are tilted, they project angularly away from the microscope body and from the zoom optical axes about which they rotate. Thus, a lever arm of substantial length is created. The length of the lever arm, which equals the distance between a point on the eyepiece near the cup and the center of the zoom optical axis about which the eyepiece rotates, is sufficient to overcome any opposing forces caused by the spring loading, etc. which may cause binding.
In a second type of stereomicroscope, such as is used by the electronics industry, it is oftentimes desirable to dispose the eyepieces so that they are parallel to the optical axes of the instrument. The rationale for such an arrangement is that the entire microscope is mounted at an angle to another instrument. The angle of mounting would cause the tipped eyepieces of the previously described microscope to project at an awkward and uncomfortable angle. Thus, a straight or parallel mount is required.
Normally, in instruments which are specifically designed for mounting to another instrument, the design of the optics and mechanics are worked out simultaneously. Accordingly, there is a cohesive interaction of all parts.
However, it is quite costly for a manufacturer to design and build separate microscopes for each specific task. Therefore, many advantages may be gained if one basic microscope could be designed which, with certain modifications, could be readily adapted to be used either as a stand alone instrument (with inclined eyepieces) or in conjunction with additional apparatus (with straight through eyepieces).
Accordingly, it is an object of the present invention to provide a stereomicroscope which may be utilized for various and diverse microscopic tasks.
Other objects and advantages of the invention will become apparent from the following description.